Regarding validity of loan documents

Could anyone pls clarify my doubts.. 1) when can a debt be called time barred in banks? does it depends only on promisory note or also on other documents like hypothecation agreement,letter of guarantee etc executed during sanction. 2) what is the validity period of those documents?like hypothecation agreement,letter of undertaking,leeter of guarantee etc.. 3) should the banker obtain all the fresh documents,as and when expired?i heard from banker that it is sufficient to obtain debit balance confirmation wherever necessary and automatically all the remaining documents will be validated.but i dnt think dats right.. So pls extend your help in clarifying these.Thanks in advance....